Measuring dimensions of a shaped three dimensional body is done today using coordinate measuring machines (C.M.M.). These systems are built using accurately manufactured and assembled mechanical parts.
This dependence on mechanical precision in order to acquire and maintain the measuring accuracy has severe drawbacks.
1. The cost of the C.M.M. is high due to the high cost of its accurate mechanical parts and the complexity of construction. PA1 2. Accuracy of the coordinate measuring machine can be maintained only under controlled environmental conditions, usually in a clean, air-conditioned room. PA1 3. Keeping the accuracy of the system in time calls for periodical calibration actions which are complicated and expensive.
These drawbacks restrict the use of the traditional coordinate measuring machines only to post process quality control applications, because C.M.M. machines are used only in environmentally controlled rooms, physically separated from the production line.
The underlying concept of the present invention is to continuously measure the inaccuracies of the measuring system in all dimensions. In doing so, the accuracy of the measuring system no longer depends on the inherent accuracy of the mechanical construction, hence the C.M.M. can be produced using less accurate and therefore less expensive components. The C.M.M. has further built in accuracy monitoring and calibration. The system can be put in the manufacturing plant next to the production line without any reduction in its operational accuracy.
The method used to monitor the inaccuracies of the C.M.M. is electro-optical. And the principle of operation is based on measuring and calculating all angular and lateral misalignments of each moving axis of the C.M.M. in all of its six degrees of freedom. By using electro-optical measuring methods combined with computer based analysis of the measurement results, an accurate position analysis of the measuring probe, used by the C.M.M. is generated and results in a long lasting, in process, accurate measurement of manufactured parts.